Dithiopentacene derivatives, their preparation and the use thereof as electron acceptors in charge transfer complexes

A charge-transfer complex of formula II

• [(A).sub.p ].sup.q.crclbar. B.sup.q.sym. (II)
• wherein
• a) A is the radical anion of a compound of formula I or of a mixture of compounds of formula I ##STR6## wherein the R substituents are identical and are H or C.sub.1 -C.sub.4 alkyl, the adjacent R substituents, taken together, are --(CH.sub.2).sub.3 -- or --(CH.sub.2).sub.4 --;
• R.sub.1 is H or C.sub.1 -C.sub.4 alkyl;
• and X.sub.1 is .dbd.N--CN, and X.sub.2, X.sub.3 X.sub.4 are .dbd.O or .dbd.N--CN, and
• b) p and q are 1, and
• B is the monovalent radical cation of a compound of formula IIIa or IIIb ##STR7## wherein R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently of one another H, linear or branched C.sub.1 -C.sub.18 alkyl-(Z.sub.1).sub.n --, phenyl-(Z.sub.1).sub.n -- or benzyl-(Z.sub.1).sub.n -- which are unsubstituted or substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy or C.sub.1 -C.sub.4 alkylthio, or R.sub.2 and R.sub.3 as well as R.sub.4 and R.sub.5 are each independently of the other trimethylene, tetramethylene, --Z.sub.2 --(CH.sub.2)--Z.sub.2 --, --Z.sub.2 --(CH.sub.2).sub.2 --Z.sub.2 --, --Z.sub.1 --CH.dbd.CH--Z.sub.1 -- or --CH.dbd.CH--CH.dbd.CH--, each unsubstituted or substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy or C.sub.1 -C.sub.4 alkylthio, n is 0 or 1 steht, Y.sub.1 and Y.sub.2 are each independently of the other --S-- or --Se--, Z.sub.1 is --S-- or --Se--, Z.sub.2 is --O--, --S-- or --Se--, Z is --S--, --Se-- or NR.sub.7, and R.sub.7 is H, C.sub.1 -C.sub.6 alkyl, phenyl or benzyl, and R.sub.6 is H, C.sub.1 -C.sub.4 alkyl, phenyl or benzyl;
• or B is the monovalent radical cation of an N-aromatic compound containing a total of 1 to 5 unsubstituted or halogen-, C.sub.1 -C.sub.4 alkyl-- or C.sub.1 -C.sub.4 alkoxy-substituted aromatic rings, at least one of which rings contains at least one --NR.sub.8 -- or [.dbd.N.sup.+ R.sub.8 --] I.sup.- group, wherein R.sub.8 is C.sub.1 -C.sub.4 alkyl or benzyl;
• or
• c) p and q are 2 and
• B is a radical cation of an N-aromatic compound as defined above;
• or
• d) p is 2 and q is 1 and
• B is unsubstituted ferrocene or Fe(indenyl).sub.2 or ferrocene or Fe(indenyl).sub.2 which are substituted by C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 hydroxyalkyl, amino-C.sub.1 -C.sub.6 alkyl, primary or secondary amino-C.sub.1 -C.sub.6 alkyl containing 1 to 12 carbon atoms in the primary amino group and 2 to 12 carbon atoms in the secondary amino group, NH.sub.2, primary amino containing 1 to 12 carbon atoms, or secondary amino containing 2 to 12 carbon atoms.